The present invention relates to a quick release coupling, more particularly but not exclusively intended for hose pipe assemblies to be used at sea.
To transfer products in liquid, powdery or paste form between two either on-shore or off-shore installations, such as ships, pontoons, barges or fixed on-shore installations, or between a ship and an off-shore drilling platform, it is conventionally known to use hose pipes, namely non rigid pipes, in order to allow the relative displacements of their ends, displacements which are caused for example by the swell.
FIG. 1 hereto illustrates the special case of a ship 3 tied to an off-shore drilling platform 4 by way of a flexible pipe 2, which flexible pipe 2 is connected either to the ship 3 or to the platform 4 by way of a quick release coupling, respectively 5a-5b. Said coupling is designed to disconnect instantly the ship from the platform so that if the need arises, because for example of a well blowing out or a storm starting, the ship can sail away from said platform before it can drift towards it or sink with it.
A coupling of this type is already known from U.S. Pat. No. 3,847,413, which consists of a male coupling section fitting into a female coupling section integral with an annular locking assembly covering the male section, on either side of the fitting in area. The locking assembly is composed on the one hand of diametral walls and annular walls, defining an annular chamber, and on the other hand, of a hydraulic piston movable inside said chamber between a locking position and an unlocking position, locking ball elements being further provided in the radial bores of the inner annular walls and being insertable in spherical recesses provided in the male tubular element.
Due to the fact that a longitudinally moving piston is used both for initiating the locking and for the actual locking and unlocking operations the locking assembly is very long.
Also, due to the high pressures which prevail inside the coupling reaching up to 1000 bars, it is important to produce joints with hardly any play and of great length, which of course adds even more to the overall length of the assembly.
With this construction, when disconnecting, and just when the locking assembly is in the unlocking position, it may happen that two tubular male and female elements of the coupling do not separate one from the other due to a jamming of their contacting surfaces. The jamming is due to the reciprocal jointing length, to to the fact that there is little play in the joint, to the external conditions causing a misalignment of the male and female elements, and to the pressure prevailing inside the coupling which pressure generates hydraulic plastering phenomena.
Another coupling is also known wherein the male and female connection members are pressed together tightly end-to-end, by way of a peripheral clamp comprising a plurality of longitudinal independent fingers capable of oscillating between a locking position and an unlocking position in relation to the displacements of an annular piston in contact with their outer face. Each finger is provided, first, at one of its ends, with opposed truncated faces giving it a hooked shape and abutting, in the locking position, against the complementary truncated faces provided on the two flanges on either side of their contacting area and, second, with a sloping back face which, in the unlocking position, abuts against the periphery of one of the flanges. It can happen, with this kind of coupling, that when the two flanges are disconnected, and despite the longitudinal components which are due to the pressure and tend to move the two flanges apart, that the flange which is not associated to the fingers remains hooked under one or more of those fingers. In addition, this device, being composed of a large number of precise parts, is rather costly.